The present invention relates to an injection syringe of the type including, on the one hand, an elongate syringe body comprising a tube and a front wall equipped with an injection needle, and, on the other hand, a rear actuating plunger mounted so as to be displaceable inside the tube.
Syringes of the abovementioned type are known which are used in particular for performing subcutaneous or intramuscular injections in the body of a patient.
The growth of diseases transmitted via the blood has led to the development of disposable syringes which are discarded after the injection has been completed. These syringes can be supplied either filled with the substance to be injected, or else empty, in which case the substance to be injected is pumped through the injection needle by means of the suction obtained on pulling the rear plunger.
The known syringes present a danger to the operator immediately after the withdrawal of the needle from the patient""s body at the end of the injection. This is because the operator risks pricking himself or herself with the point of the needle and being contaminated by the residual traces of blood which it bears.
In order to limit the danger presented by the point of the needle, protective caps have been proposed which the operator fits onto the syringe body in order to cover the needle. However, given that the cap has to be put into position manually, the operator may forget to fit it, or else may be pricked by the needle when putting the cap into place. Moreover, the cap cannot be put into place at the same time as the needle is being withdrawn from the patient""s body, and so the needle remains unprotected for a brief moment
The object of the invention is to make available an injection syringe which eliminates any risk of the operator being pricked by the point of the needle after the end of the injection.
To this end, the invention relates to an injection syringe of the abovementioned type, which is characterized in that it is equipped with a mobile needle protector which can be displaced in relation to the body, under the effect of the actuating plunger being driven into the body, and during this actuation, between a retracted position, set back from the injection end of the needle, and an active protection position, in which the front end of the protector is situated in front of the injection end of the said needle.
Depending on specific embodiments, the invention can have one or more of the following characteristics:
the body includes at least one opening for the passage of the protector, of which a rear end, situated inside the syringe body, forms a surface for actuation by the rear plunger for the forward displacement of the protector;
the injection needle protrudes inside the syringe body, and the inside of the tube is provided with a mobile front plunger interposed between the protector and the rear actuating plunger, the two plungers delimiting a space for the fluid which is to be injected;
prior to the use of the syringe, the front plunger is arranged behind the needle, and the front plunger is designed to be punctured by the proximal end of the needle when the rear plunger is driven in;
the protector and the body include complementary means for temporarily maintaining the protector in its retracted position, these means being designed to withstand the thrust exerted by the front plunger on the protector when the rear plunger is being driven into the tube, while the rear plunger is behind the proximal end of the needle or the said front plunger;
the opening, or each opening, is formed in the front wall;
the protector includes a protective ring arranged outside the body around the axis of the needle, which ring is continued via at least one leg received in an opening of the body, and, in the active protection position, surrounds the injection end of the needle;
the mobile needle protector is mounted so as to slide on the outside of the syringe body;
the mobile needle protector includes, on the one hand, an end sheath for protecting the needle, and, on the other hand, means for connecting the said end sheath to the actuating plunger, which connecting means extend externally along the syringe body as far as the end of the plunger protruding from the body;
the mobile needle protector is fixed to the actuating plunger;
the mobile needle protector and the syringe body include complementary means for temporarily maintaining the protector in its retracted position;
the mobile needle protector is essentially tubular and includes longitudinal slots, the syringe body including, at its open end, radial actuating lugs which protrude from the said mobile needle protector through the said slots;
the protector and the body include complementary means for locking the protector on the body in its active protection position;
the locking means include complementary protruding and hollowed portions formed on the inner wall of the syringe body and on the leg, or each leg, of the protector;
the injection needle protrudes inside the syringe body, and the rear plunger is equipped, opposite the proximal end of the needle, with a sealing membrane which can be punctured by the said proximal end of the needle once the plunger has been driven into the body;
the rear plunger is connected to an actuating rod including an axial recess for receiving the proximal end of the needle, arranged behind the said membrane; and
the said recess is delimited by a solid wall equipped with one or more calibrated vents for communication with the surrounding atmosphere.
The invention will be better understood on reading the following description which is given solely by way of example and in which reference is made to the drawings, in which: